Vacuum relay



June 28, 1966 v 5 DE uc 3,258,559

VACUUM RELAY Filed May 1.7, 1965 Non-magnetic Disc 60 F lg.

Energizing Coil 58 Terminals 60 Victor E. De Lucio,

INVENTOR.

My, M

ATTORNEY.

United States Patent 3,258,559 VACUUM RELAY Victor E. De Lucia, 927Euclid Ave., Santa Monica, Calif. Filed May 17, 1965, Ser. No. 456,148 6Claims. (Cl. 200-87) The present invention relates to vacuum relays ofthe solenoid-operated type, and it relates more particularly to animproved vacuum relay of the type in which the pole pieces of themagnetic circuit thereof extend into the interior of the evacuatedchamber for controlling the operation of the movable internal parts ofthe relay.

Vacuum relays are in general known to the relay and switching art. Theserelays are particularly advantageous in that they are capable ofrelatively high voltage operation and of relatively high currentcarrying capabilities without suffering contact erosion or the like.

The vacuum relay is also advantageous because it is generally unaffectedby changes in atmospheric pressure or humidity. In addition, vacuumrelays may be constructed to the substantially immune from vibrationeffects and to be able to withstand relatively high accelerationswithout affecting its switching capabilities.

The general type of vacuum relay with which the pres- 'ent invention isconcerned includes a envelope formed of glass, or other vitreous ordi-electric material. The envelope of this general .type of vacuum relayhas a metallic end wall of non-magnetic material through which themagnetic core of the magnetic circuit of the relay extends, and the endwall is sealed to the envelope to form therewith an evacuated chamber.

The armature of .the type of relay with which the invention is concernedis pivotally mounted Within the chamber for movement towards and awayfrom the end of the aforementioned core. A spring biasing means urgesthe armature away from the end of the core, and when the relay isenergized, the armature is drawn down in a pivotal manner towards theend of the core. A movable contact is mounted on the armature, and thismovable contact is caused selectively to engage fixed contacts in theevacuated chamber as the relay is energized and de-energized.

The present invention is particularly concerned with the structuralcomposition of the magnetic circuit and energizing coil of the vacuumrelay. In accordance with the concepts of one of the aspects of theinvention, one end of .the glass envelope of the vacuum chamber isinitially open, and an annular flange is sealed into the peripheral edgeof the vitreous envelope in position to surround the open end. Thisflange may be formed of a suitable non-magnetic metal or alloy, whichexhibits a coeflicien-t of expansion closely matching the coeflicient ofexpansion of the glass envelope. A suitable alloy for this purpose, forexample, is Kovar.

The flanged open end of the envelope of the vacuum relay to be describedis closed by a composite disc-like Wall assembly. The composite wall hasan outer ringshaped member formed, for example, of Kovar, and thismember is welded to the above-mentioned flange, for example, by aheliarc weld. A ring-shaped or annular pole piece composed ofmagnetizable material, such as iron,' is positioned concentricallywithin the outer ring shaped member of the composite wall, and this polepiece is brazed to the ring-shaped member, for example, by a copperbraze.

The composite end wall of the vacuum relay to be described also includesa further ring-shaped member which is composed of a non-magneticmaterial such as, for example, a copper-nickel alloy. This latterringshaped member is mounted in nested concentric relationship with theabove-mentioned ring-shaped pole piece,

and it is brazed to the pole piece, for example, by a copper braze.

Finally, the composite end wall of the vacuum relay to be described iscompleted by a central pole piece composed of magnetizable material,such as iron. The central pole piece is brazed to the aforementionednonmagnetic ring-shaped member by, for example, a copper braze. It willbe appreciated that the composite end Wall assembly closes the open endof the vitreous envelope, and that the composite end Wall and theenvelope together define the evacuated chamber for the vacuum relay.

The above-mentioned construction in accordance with the teachings of theinvention is advantageous in that it enables the magnetic circuit of therelay to project into the evacuated chamber, and yet it provides for aminmum of mass of magnetic core structure in the chamber itself. Thissimplifies the fabrication of the relay from an out-gassing andevacuating standpoint. This improved construction also reduces therequired amount of high purity iron, compatible with the vacuumenvironment, to .a minimum, as compared with the prior art relays ofthis general type.

The energizing coil for the relay to be described herein, and themagnetic core structure associated with the energizing coil, is formedas a separate energizing unit. This separate energizing unit is adaptedto be mounted on the external surfaces of the aforementoned ringshapedand central pole pieces.

The energizing unit of the embodiment of the invention to be describedhas a central core which contacts the external surface of the centralpole piece when the energizing unit is mounted in place, and theenergizing unit also includes a cylindrical-shaped housing ofmagnetizable material, such as iron, the ring-shaped upper peripheraledge of which contacts the outer surface of the ring-shaped pole piece,when the energizing unit is mounted in place.

The energizing coil is mounted on the central core of the energizingunit within the cylindrical housing. The end wall of the energizing unitremote from the relay chamber is composed of magnetizable material, andsuitable terminals for the energizing coil extend through the end Wall.

It is, accordingly, an object of the present invention to provide animproved vacuum relay in which the evacuated chamber is formed in anovel and improved manner, and in which the major portion of themagnetic core structure of the relay is positioned outside the evacuatedchamber and as a unit separate from the components of the evacuatedchamber.

A further object is to provide such an improved vacuum relay in whichthe mass of magnetic structure actually Within the evacuated chamber is,accordingly, reduced to a minimum.

Another object of the invention is to provide such an improved vacuumrelay which is relatively simple and economical to manufacture, in thatthe evacuated chamber and the internal moving parts can be assembled andtested as a separate unit, prior to the inclusion of the energizing unitinto the relay assembly.

Yet another object of the invention is to provide such an improvedvacuum relay which is relatively easy to service and repair, in that theenergizing unit may be easily and simply removed from the relaystructure without alfecting in any manner the internal components of therelay, or the evacuated state of the evacuated chamber.

Another object is to provide such an improved vacuum relay in which themovable contact thereof is mounted in an improved manner so as toperform its circuit making or breaking function effectively andefliciently.

Other features, objects and advantages of the invention will becameapparent from a consideration of the following description, when thedescription is considered in conjunction with the accompanying drawing,in which:

FIGURE 1 is a side sectional view of a vacuum relay constructed inaccordance with the concepts of one embodiment of the invention;

FIGURE 2 is a cross-sectional view of the relay of FIGURE 1 takensubstantially on the line 2-2 of FIG- URE l, and particularly showingthe manner in which the movable contact of the relay selectively engagescertain fixed contacts thereof;

FIGURE 3 is a bottom view, substantially on the line 3-3 of FIGURE 1, ofthe vacuum chamber portion of the relay;

FIGURE 4 is a cross-sectional view, like FIGURE 2, but showing amodified construction;

FIGURE 5 is a perspective View of the movable contact of the relay ofFIGURE 1 and the manner in which .it is mounted in the relay; and

FIGURE 6 is a side elevation of the movable contact.

The vacuum relay shown in FIGURES 1 and 2 includes an envelope 10 formedof glass, for example, or other vitreous material. In the embodimentunder consideration, the envelope 10 has a generally cylindricalconfiguration, and it is closed at one end and open at the other.

A flanged member 12 is sealed into the peripheral edge of the vitreousenvelope 10, and the flange member surrounds the open end of theenvelope. This flange member, as mentioned above, may be formed ofKovar, or other metal or alloy having a coefficient of expansionmatching that of the envelope 10.

The open end of the vitreous envelope 10 is closed by a compositemetallic end wall having a disc-shaped configuration. This end wallincludes an outer metallic ringshaped member 14. The ring-shaped member14 is also formed of a low expansion metal or alloy such as Kovar, andthis ring is attached to the flange member 12 by, for example, a heliarcweld. As annular pole piece 16 is brazed, for example, to the member 14.The annular pole piece 16 is composed of a magnetizable material, suchas iron.

The end Wall also includes a central pole piece 18, composed of amagnetizable material such as iron. An annular-shaped member ofnon-magnetic material, such as copper-nickel alloy, for example, isinterposed between the annular pole piece 16 and the central pole piece18. The member 20 is brazed to the pole pieces 16 and 18, so that themembers 14, 16, 18 and 20 combine to form a composite metallic end wallfor the vitreous envelope 10. The various members which form the endwall are sealed to one another, for example, by welding, as mentionedabove; and the ring-shaped member 14 is sealed to the flange 12, so thatthe composite end Wall, in conjunction with the vitreous envelope 10,forms an evacuated chamber for the vacuum relay.

An armature 22, composed of magnetizable material :such as iron, ispivotally mounted in the evacuated chamber adjacent the central polepiece 18. A resilient coil :spring 23 is positioned between the annularmember 20 :and the under side of the armature 22, so that the armatureis normally biased in a clockwise direction away from the central polepiece 18. However, when the relay is energized, the armature is drawn ina counterclockwise direction pivotally down onto the pole piece 18.

A rod 24 of insulating material, such as sapphire, for example, ismounted on the armature 22 by means of a clip 26. The rod 24 extendsessentially perpendicularly to the upper surface of the armature 22.

A plurality of rigid conductive contact pins 28, 30 and 32 extendthrough the envelope 10 and into the evacuated chamber in positionsillustrated in FIGURE 2. These pins constitute'the fixed contacts of therelays, and appropriate terminals 28a, 30a and 32a are provided forreceiving connections to the respective pins.

The end of the inner end of the contact pin 32 is slotted, and aconductive leaf-shaped movable contact 34 is pivotally mounted in theend slot of the pin 32. This leaf-like movable contact is also rotatablymounted on the end of the rod 24 by means of a clip 35 (FIGURES 5 and6). The clip 35 may be composed, for example, of a suitable materialsuch as molybdenum or iron. The leaf contact 34 may appropriately bemade of tungsten. The contact 34 is silver or copper brazed, forexample, to the clip 35. When tungsten is used for the contact, itssurface may be brought to a high polish, and this reduces the chances ofcontact arcing due to high fields around the contacts.

The arrangement is such that when the armature 22 is drawn down onto thepole piece 18, the movable contact leaf 34 is caused to break itsconnection with the inner end of the pin 30, and to make connection withthe inner end of the pin 28. The pin 32, therefore, forms the commonpole of the relay, and it selectively breaks contact with the pin 30 andmakes contact with the pin 28, when the relay is energized.

The rod 24 is preferably coated with silver, or other suitable material.The resulting silver-iron contacting surfaces, between the coated rodand the clip 35, have a low coeflicient of friction. This is because thesilver acts as a lubricant in high vacuum and thereby provides for aminimum of galling and low coefficient of friction.

In accordance with the concepts of the invention, and as mentionedbriefly above, a separate energizing unit 50 is provided. Thisenergizing unit includes a cylindricalshaped outer housing 52 composedof magnetizable material, such as iron. One end of the housing isenclosed by an end wall 54 which also is composed of a magnetizablematerial, such as iron. A central core 56 extends along the longitudinalaxis of the energizing unit from the end wall 54 along the length of theunit. A threaded stud 57 extends from the end of the core 56, and thisstud is received by a threaded aperture in the outer surface of the polepiece 18, so that the energizing unit 50 may be conveniently mounted onthe external surface of the composite end wall of the vacuum chamber ofthe relay.

When the energizing unit 58 is mounted on the end wall, the end of thecore 56 is in contact with the outer surface of the pole piece 18, andthe peripheral edge of the housing 52 is in contact with the annularpole piece 16. A magnetic circuit is formed, therefore, from the polepiece 18 through the central core 56, through the housing 52, to theannular pole piece 16 and to the armature 22.

An energizing coil 58 is mounted on an insulating bobbin 60, whichbobbin may be relatively thin, to permit close magnetic coupling betweenthe coil and the magnetic circuit. Terminals 60 for the energizing coil58 extend through the end wall 54, and are insulated from the end wall.

The embodiment shown in FIGURE 4 is a single normally-open contactconfiguration. In this latter embodiment, the movable contact 34 isnormally spring biased against an insulating projection 60 by means of aspring 24. In this embodiment the contact 34 rests against the edge ofthe contact pin 32 instead of in the slot, as' in FIGURE 2. When therelay is energized, the movable contact is drawn against the contact pin28 to establish contact between the pin 32 and the pin 28.

It is desirable to remove residual gases and water vapor from theevacuated interior of the envelope 10 prior to using the relay. However,the usual flush type chemical getters have a tendency to createconductive short-circuiting films on the interior surface of theenvelope.

To achieve gettering action in the embodiment of the invention underconsideration, without adverse effects, a coating of gettering material62 may be placed on the internal surface of the flange member 12 and/oron the internal surface of the ring-shaped member 14.

The gettering material may be an alloy of cerium known to the trade asCerAlloy 400, and composed of thorium, aluminum and cerium. This alloyis most effective in reducing hydrogen, carbon monoxide, methane, watervapor, oxygen and carbon dioxide, etc., during normal operatingtemperatures of the relay and without any adverse or deleteriouseffects. About 12% titanium can be added to increase the absorbingeffectiveness of the alloy with respect to hydrogen.

The coating 62 of gettering material can be placed on the rear surfaceof the contact 34, as shown in FIGURE 6. A relatively high current canbe passed through the relay to heat the contact and increase theeffectiveness of the gettering action. If desired, the getteringmaterial may be coated on a separate strip which, in turn, is spotwelded or otherwise affixed to the rear surface of the contact.

A description of the gettering action of CerAlloy 400 is contained, forexample, in ASD Technical Report 61- 268, entitled Ceramic ReceivingTube Refinement Program by Bruce E. Barnaby, released to the Ofiice ofTechnical Services, United States Department of Commerce, for sale tothe public.

The invention provides, therefore, an improved vacuum relay which isrelatively simple to construct and test; and one which is conceived tohave a minimum of magnetic parts and surface area in the evacuatedchamber itself.

While particular embodiments of the invention have been shown anddescribed, modifications may be made, and it is intended in the claimsto cover all such modifications as fall within the spirit and scope ofthe invention.

What is claimed is:

1. A vacuum relay including: an envelope having a discontinuous endportion; a composite wall including a central pole piece of magnetizablematerial, an annular pole piece of magnetizable material surroundingsaid central pole piece in concentric relationship therewith and spacedradially therefrom, and an annular member of non-magnetic materialinterposed between said central pole piece and said annular pole piece;means for sealing said composite wall to said envelope to enclose saidend portion thereof and to constitute therewith a vacuum chamber; anarmature mounted within said vacuum chamber adjacent said central polepiece; resilient means for normally biasing said armature away from saidcentral pole piece; fixed contact means mounted on said envelope andextending into said vacuum chamber; movable contact means mounted onsaid armature for selectively engaging said fixed contact means; anenergizing unit mounted externally of said vacuum chamber and includinga central core member of magnetizable material in magnetic contact withthe external surface of said central pole piece and further including ahousing of magnetizable material in magnetic contact with the outersurface of said annular pole piece; and said energizing unit includingan energizing coil mounted on said central core member and positioned insaid housing.

2. The relay defined in claim 1 and which includes a metallic flangemember sealed to said envelope and surrounding said end portion thereof,and an outer annular metallic member included in said composite wallsealed to said annular pole piece and to said flange member for mountingsaid composite wall on said envelope.

3. The relay defined in claim 1 in which said central pole piece has athreaded aperture in the external surface thereof, and which includes athreaded stud extending outwardly from said central core member of saidenergizing unit to be received in said threaded aperture in said centralpole piece to mount said energizing unit on the external surface of saidcomposite end wall.

4. The relay defined in claim 1 in which said housing of said energizingunit has a cylindrical configuration, and said housing includes an endwall of magnetizable material enclosing the end thereof remote from saidcomposite end wall, and said central core member extends along thelongitudinal axis of said energizing unit from said end wall thereof.

5. A vacuum relay including: an envelope having a discontinuous portion;an essentially uniplanar composite wall including a central pole pieceof magnetizable material, an annular pole piece of magnetizable materialsurrounding said central pole piece in spaced concentric relationshiptherewith, and an annular member of non-magnetic material interposedbetween said central pole piece and said annular pole piece; a metallicflange member sealed to said envelope and surrounding :saiddiscontinuous portion thereof; and an outer annular metallic memberincluded in said composite wall and sealed to said annular pole pieceand to said flange member for mounting said composite wall on saidenvelope.

6. A vacuum relay including: a vitreous envelope having a discontinuousportion; an essentially uniplanar composite wall including a centralpole piece of magnetizable material and including an external threadedportion for receiving a mating pole piece of an external energizing coilassembly, an annular pole piece of magnetizable material surroundingsaid central pole piece in spaced concentric relationship therewith andhaving an external surface for receiving a mating annular pole piece ofsaid external coil assembly, and an annular member of non-magneticmaterial interposed between said central pole piece and said annularpole piece; a metallic flange member sealed to said envelope andsurrounding said discontinuous portion thereof; and an outer annularmetallic member included in said composite wall and sealed to saidannular pole piece and to said flange member for mounting said compositewall on said envelope.

References Cited by the Examiner UNITED STATES PATENTS 11/1959 Jennings200-87 9/1961 Racz et a1. 200l44

5. A VACCUM RELAY INCLUDING: AN ENVELOPE HAVING A DISCONTINUOUS PORTION;AN ESSENTIALLY UNIPLANAR COMPOSITE WALL INCLUDING A CENTRAL POLE PIECEOF MAGNETIZABLE MATERIAL, AN ANNULAR POLE PIECE OF MAGNETIZABLE MATERIALSURROUNDING SAID CENTRAL POLE PIECE IN SPACED CONCENTRIC RELATIONSHIPTHEREWITH, AND AN ANNULAR MEMBER OF NON-MAGNETIC MATERIAL INTERPOSEDBETWEEN SAID CENTRAL POLE PIECE AND SAID ANNULAR POLE PIECE; A METALLICFLANGE MEMBER SEALED TO SAID ENVELOPE AND SURROUNDING SAID DISCONTINUOUSPORTION THEREOF; AND AN OUTER ANNULAR METALLIC MEMBER INCLUDING IN SAIDCOMPOSITE WALL AND SEALED TO SAID ANNULAR POLE PIECE AND TO SAID FLANGEMEMBER FOR MOUNTING SAID COMPOSITE WALL ON SAID ENVELOPE.